cm:Level1TextBlock: us-gaap:AssetRetirementObligationDisclosureTextBlock
| Asset Retirement Obligation Disclosure [Text Block] |
| us-gaap:AssetRetirementObligationDisclosureTextBlock |
| The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. |
| cm:Level1TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:AssetRetirementObligationDisclosureTextBlock |
| AssetRetirementObligationDisclosure |